Evaluating the Effect of Alternative Spatial Arraignments of Wetlands at the Watershed Scale

A suite of recent work has sought to identify the optimal spatial distribution of wetlands to maximize their influence upon watershed scale environmental indicators such as hydrologic flow. These studies have added to our understanding of the importance of the spatial arraignment of wetlands by determining, for example, that a disaggregated strategic creation of smaller wetlands throughout a watershed may have the same impact upon hydrologic flow as that of fewer but larger wetlands. However, these studies have yet to evaluate explicit measures of spatial arraignment as impacting environmental outcomes - for example, the spatial agglomeration exemplified by large wetland complexes or the distributed patterns characteristic of landscapes dominated by isolated wetlands. This project demonstrates a method of explicitly evaluating spatial arrangement by incorporating a graph-theory representation of wetland distribution patterns into a search algorithm and hydrologic model framework. Using the Soil and Water Analysis Tool (SWAT) and a genetic algorithm set to either maximize or minimize site connectivity as evaluated by graph-distance, this project will evaluate a range of spatial arraignments to correlate measures of connectivity with hydrologic flow as simulated by SWAT. In so doing, this project seeks to inform theory on the connectivity of wetlands at the watershed scale while also demonstrating a practical tool meant to strengthen evaluations of wetlands that use a search algorithm and hydrological model framework.